Various wireless powering methods for implantable electronics are based on nearfield or farfield coupling. These and other methods suffer from several disadvantages. A power harvesting structure in an implanted device is typically large (e.g., typically on the order of a centimeter or larger). Coils external to the body in nearfield coupling can similarly be bulky and inflexible. Such constraints present difficulties regarding incorporation of an external device into a patient's daily life. Furthermore, the intrinsic exponential decay of nearfield signals limits miniaturization of an implanted device beyond superficial depths (e.g., greater than 1 cm). On the other hand, the radiative nature of farfield signals can limit energy transfer efficiency.
Generally discussed herein are systems, devices, and methods for providing or delivering a patient therapy using an implantable device. In an example, the patient therapy includes an electrostimulation therapy provided to one or more neural targets in a patient body. In an example, the electrostimulation therapy is provided using an implantable device that wirelessly receives power and data signals from a midfield transmitter.
Wireless midfield powering technology can be used to provide power from an external power source to an implanted electrostimulation device. The external power source, or transmitter, can be located on or near a tissue surface, such as at an external surface of a patient's skin. Midfield-based devices can have various advantages over conventional implantable devices. For example, midfield powering technology need not require a relatively large implanted pulse generator and one or more leads that electrically connect the pulse generator to stimulation electrodes. A midfield device can provide a simpler implant procedure, which can lead to a lower cost and a lower risk of infection or other implant complications.
Another advantage of using midfield powering technology includes a battery or power source that can be provided externally to the patient, and thus the low power consumption and high efficiency circuit requirements of battery-powered implantable devices can be relaxed. Another advantage of using midfield powering technology can include an implanted device that can be physically smaller than a battery-powered device. Thus, midfield powering technology can help enable better patient tolerance and comfort along with potentially lower manufacturing and implantation costs.
There is a current unmet need that includes communicating power and/or data using midfield transmitters and receivers, such as to communicate power and/or data from an external midfield transmitter to or from an implanted device, such as a neural stimulation device or a sensor device.